It is shownthat using a combined control with uncertainty observer the control system with uncertain elastic multimass object can be split into subsystems, which are interconnected only through compensated uncertainty vector. Under uncertain multimass objects understood composite control objects with unknown mass-inertia characteristics, with not fully and accurately known state vector, subjected to unknown internal and external influences, and also with not exactly known control action. Each subsystem is a two-mass system with elastic links between the masses, which consists of an electric motor, elastic transmission and control object. As a result of decomposition, the construction of the entire control system is reduced to the independent design of each link control systems. Mentioned two-mass subsystem may be part of the robot, control system of metal-working machines, rolling mills, radars and many other technical devices.